Heat dissipation system

ABSTRACT

A heat dissipation system comprises a printed circuit board and at least a heat dissipation device mounted on the printed circuit board for dissipating heat generated by an electronic member mounted on the printed circuit board. The at least a heat dissipation device comprises a base, a plurality of fins extending upwardly from the base and an air guiding member located at a corner of the base. These fins are spaced from each other to define a plurality of heat exchange passages. Non-fins are disposed at a side of the base to define a cooling air passage. The cooling air passage is parallel to the heat exchange passages of the fins. The air guiding member is located in the cooling air passage for controlling open and close of the cooling air passage.

BACKGROUND

1. Technical Field

The disclosure relates to a heat dissipation system and, more particularly, to a heat dissipation system for dissipating heat generated by two electronic devices.

2. Description of Related Art

A computer system, such as a server, a workstation, often includes two electronic devices, such as two central processing units (CPUs). The CPUs produce a large amount of heat during operation. The heat must be quickly removed from the CPUs to prevent them from becoming unstable or being damaged. Typically, two heat dissipation devices are attached to outer surfaces of the CPUs, respectively.

FIG. 6 shows a heat dissipation system 2 for dissipating heat generated by the computer system mentioned above. The heat dissipation system 2 includes two heat dissipation devices 50 a, 50 b. The heat dissipation devices 50 a, 50 b are respectively attached to outer surfaces of the CPUs (not shown) mounted on a printed circuit board 60 in the computer system. The heat dissipation devices 50 a, 50 b include a substrate 51 a, 51 b and a plurality of fins 52 a, 52 b extending upwardly from the substrate 51 a, 51 b, respectively. These fins 52 a, 52 b are spaced from each other to form a plurality of passages 521 a, 521 b through which a cooling airflow flows. The heat dissipation devices 50 a, 50 b and a plurality of accessories 70 around the CPUs cooperatively form a path 80. The airflow flows through the path 80 along a direction indicated by arrows in the FIG. 6, in other words, the airflow flows through the heat dissipation device 50 a firstly, and then flows through the heat dissipation device 50 b.

During the airflow flowing through the path 80, the airflow is heated by the heat dissipation device 50 a, and a speed of the airflow is decreased. The heated and low-speed airflow flows through the heat dissipation device 50 b, and carry away little heat absorbed by the heat dissipation device 50 b from the CPU. Thus the heat dissipation capability of the heat dissipation device 50 b is lower than that of the heat dissipation device 50 a. That is to say, if the heat dissipation device 50 a has a heat dissipation capability that the computer system requires, the heat dissipation capability of the heat dissipation device 50 b is lower than the required heat dissipation capability, if the heat dissipation device 50 b achieve the required heat dissipation capability, an excessive heat dissipation performance of the heat dissipation device 50 a are used, representing considerable cost and material burdens.

What is needed, therefore, is a heat dissipation system having a balanceable heat dissipation capability.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is an isometric, assembled view of a heat dissipation device in accordance with an embodiment of the disclosure.

FIG. 2 is a partially exploded view of the heat dissipation device of FIG. 1.

FIG. 3 is an isometric, sectional view of an air guiding member of the heat dissipation device of FIG. 1.

FIG. 4 is an isometric, assembled view of a heat dissipation system utilizing the heat dissipation device of FIG. 1.

FIG. 5 is a schematic view showing air flow of the heat dissipation system of FIG. 4.

FIG. 6 is an isometric, assembled view of a heat dissipation system utilizing a heat dissipation device in accordance with related art.

DETAILED DESCRIPTION

Referring to FIG. 1, a heat dissipation device 10 a is illustrated in accordance with an embodiment of the disclosure. The heat dissipation device 10 a comprises a rectangular base 11, a plurality of parallel fins 12 extending upwardly from a top face of the base 11, four fasteners 13 fastening the base 11 on a printed circuit board 20 (see FIG. 4) and an air guiding member 15 mounted on the base 11 via one of the fasteners 13. The base 11 and the fins 12 are made of materials having a good thermal conductivity, such as copper, aluminum for efficiently absorbing heat generated by an electronic member (not shown) mounted on the printed circuit board 20 and dissipating it to the exterior. These fins 12 are spaced from each other to form a plurality of heat exchange passages 121 for heat exchanging with a cooling airflow flowing therethrough. There is non-fins disposed at a side of the base 11 to form a blank region (not labeled) for defining a cooling air passage 122 through which a branch of the cooling airflow passes. Width of the cooling air passage 122 is larger than that of the heat exchange passage 121, whereby a sufficient amount of cool air of the cooling airflow can flow through the cooling air passage 122.

Referring also to FIG. 2, each fastener 13 comprises a blot 131 with an upper head (not labeled) having a cross groove (not labeled) at a top end thereof for facilitating operation of a tool, a helical spring 132 and a gasket 133 sequentially coiled around the bolt 131. When the fastener 13 is used, the fastener 13 extends through a through hole 111 in the base 11 and the printed circuit board 20, and engages with a back plate (not shown) located below the printed circuit board 20. Simultaneously, the helical spring 132 is elastically sandwiched between the upper head of the bolt 131 and the gasket 133, such that the base 11 is secured on the printed circuit board 20 and attached to an outer, top surface of the electronic member on the printed circuit board 20.

The air guiding member 15 is made of materials having a certain elasticity, such as plastic or rubber. The air guiding member 15 is rested in the cooling air passage 122 on the base 11 for controlling open and close of the cooling air passage 122. In this illustrated embodiment, the air guiding member 15 is located at an intake of the cooling air passage 122 and mounted at a corner of the base 11 via one of the fasteners 13. In other uses, the air guiding member 15 can be located at any position of the cooling air passage 122 by other means.

The air guiding member 15 comprises a cylindrical holder 153, a cylindrical body 152 pivotally engaging with a top of the holder 153, and a wing 151 integrally extending from an outer surface of the cylindrical body 152.

Referring also to FIG. 3, four evenly spaced substantially V-shaped slots 1532 are defined in an inner wall of the holder 153. Two adjacent V-shaped slots 1532 each have an acute angle or a right angle (i.e., not larger than 90 degrees), and the other two adjacent V-shaped slots 1532 each have an obtuse angle (i.e. larger than 90 degrees). The body 152 is cylinder and has a tie-in 1521 at a bottom end thereof. The tie-in 1521 protrudes two clasps 1522 at two opposite sides thereof for selectively engaging in one of the two adjacent slots 1532 having an angle not larger than 90 degrees and one of the other two adjacent slots 1532 having an angle larger than 90 degrees, respectively. The wing 151 is a rectangular board. A height of the wing 151 is identical to that of the fins 12, and a width thereof is identical to that of the cooling air passage 122. In this embodiment, a top of the wing 151 is flush with a top of the body 152. The height of the wing 151 is identical to a sum of a height of the holder 153 and a height of the body 152 minus a height of the tie-in 1521. The bolt 131 of the fastener 13 extends through the spring 132, the body 152, the holder 153, and the gasket 133 in sequence to secure the air guiding member 15 on the base 11 and prevent it from rotating with respect to the base 11.

When one of the clasps 1522 of the body 152 is blocked in a corresponding acute-angled or right-angled slot 1532 of the holder 153, the wing 151 is positioned parallel to the cooling air passage 122 of the heat dissipation device 10 a, and the cooling air passage 122 is open so that the branch of the cooling airflow can flow through the cooling air passage 122; when the body 152 rotates 90 degrees with respect to the holder 153 to make the one of the clasps 1522 of the body 152 is blocked in the other one acute-angle or right-angled slot 1532, the wing 151 is positioned perpendicular to the cooling air passage 122, and the cooling air passage 122 is closed so that the branch of the cooling airflow is blocked by the wing 151. The body 152 is pivotably connected to the holder 153, and the wing 151 is located at the required position by a rotation of the body 152 relative to the holder 153.

Referring to FIG. 4, a heat dissipation system 1 utilizing the heat dissipation device 10 a is illustrated. The heat dissipation system 1 comprises a heat dissipation device 10 a disclosed above, a heat dissipation device 10 b similar to the heat dissipation device 10 a, the printed circuit board 20 and a plurality of accessories 30 around the heat dissipation devices 10 a, 10 b. The accessories 30 in this embodiment are DRAM modules. The heat dissipation devices 10 a, 10 b are mounted on the printed circuit board 20 via the fasteners 13, 13 b side by side for dissipating heat generated by two electronic members on the printed circuit board 20. The heat dissipation device 10 a, 10 b and the accessory 30 cooperatively form a path 40 through which the cooling airflow passed. The heat dissipation device 10 a is located at an intake of the path 40, and the heat dissipation device 10 b is located at an outtake of the path 40. The wing 151 of the heat dissipation device 10 a is rotated to a position parallel to the fins 12, whereby the cooling air passage 122 is opened. Simultaneously, the wing 151 b of the heat dissipation device 10 b is rotated to a position perpendicular to the fin 12, whereby the cooling air passage 122 b is closed. Each of the air guiding members 15 is located at a corner of a windward side of the base 11 of the corresponding heat dissipation device 10 a (10 b), whereby an entrance of the cooling passage 122 b is closed, and the cooling air which flows through the cooling passage 122 a can almost flow into the heat exchange passages 121 b to effectively take heat away from the heat dissipation device 10 b.

Referring also to FIG. 5, the cooling airflow flows along a direction indicated by arrows in the path 40. A part of the cooling airflow flows through the heat exchange passages 121 of the fins 12 of the heat dissipation device 10 a and exchanges heat therewith, and the other part of the cooling airflow, that is to say, the branch of the cooling airflow directly flows through the cooling air passage 122 without being blocked by the wing 151. Then, the heated airflow by the fins 12 of the heat dissipation device 10 a and the branch of the cooling airflow together flow through the heat dissipation device 10 b. As blocked by the wing 151 b of the heat dissipation device 10 b, all of the airflows flowing through the heat dissipation device 10 a flow through the cooling air passages 121 b of the fins 12 b and exchanging heat therewith. Accordingly, the heat dissipation system 1 can more effectively cool two electronic members arranged in series along an airflow path.

In the heat dissipation system 1, amount of airflow flowing through the heat exchange passages 121 of the heat dissipation device 10 a is smaller than that flowing through the heat exchange passage 121 b of the heat dissipation device 10 b. The increased amount of airflow through the heat dissipation device 10 b compensates the increase of temperature of the airflow through the heat dissipation device 10 b, to thereby achieve a balance of heat dissipation capabilities between the heat dissipation devices 10 a, 10 b. To improve heat-dissipating efficiency of the heat dissipation system 1, the exit of the cooling air passage 122 of the heat dissipation device 10 a faces the heat exchange passages 121 b of the heat dissipation device 10 b. The heat dissipation devices 10 a, 10 b are the same from each other regarding the configuration and structure to improve an interchangeability of the heat dissipation devices 10 a, 10 b for further reducing a designing cost of the heat dissipation system 1.

Alternatively, when one electronic member which engages the heat dissipation device 10 a works and the other one electronic member which engages the heat dissipation device 10 b stops, the wing 151 of the heat dissipation device 10 a is rotated perpendicular to the fins 12 to close the cooling air passage 122, and the wing 151 b of the heat dissipation device 10 b is rotated parallel the fins 12 to open the cooling air passage 122 b. Thus, the amount of the airflow flowing through the heat exchange passages 121 of the heat dissipation device 10 a is increased whereby the heat dissipation devices 10 a has a great heat dissipation capability. Simultaneously, the airflow heated by the heat dissipation device 10 a flows through the heat dissipation device 10 b and exchanges heat with the heat dissipation device 10 b to decrease the temperature of the heat dissipation system 1. The temperature of the dissipation system 1 can be kept as low as possible.

It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A heat dissipation system comprising: a printed circuit board; at least a heat dissipation device mounted on the printed circuit board and comprising: a base secured to the printed circuit board and adapted for engaging an electronic member mounted on the printed circuit board; a plurality of fins extending upwardly from a top face of the base, the fins defining a plurality of heat exchange passages therebetween; a cooling air passage defined over the top face of the base, located beside the fins and being parallel to the heat exchange passages of the fins; and an air guiding member located in the cooling air passage for controlling open and close of the cooling air passage to enable airflow to flow through the cooling air passage, or block the airflow from flowing through the cooling air passage.
 2. The heat dissipation system as claimed in claim 1, wherein the air guiding member comprises a holder secured on the base, a body pivotally engaging a top of the holder, and a wing integrally extending from an outer surface of the body.
 3. The heat dissipation system as claimed in claim 2 further comprising a fastener securing the holder of the air guiding member on the base for preventing the holder from rotating with respect to the base.
 4. The heat dissipation system as claimed in claim 3, wherein the fastener comprises a bolt extending through the holder of the air guiding member and a spring sandwiched between the holder and an upper head of the bolt.
 5. The heat dissipation system as claimed in claim 2, wherein the body has a tie-in at a bottom end thereof, the tie-in protruding two clasps at two opposite sides thereof, the holder defining four evenly spaced slots in an inner wall thereof, the clasps of the tie-in clasping with corresponding two of the four slots for positioning the wing of the air guiding member at one of positions for controlling open and close of the cooling air passage.
 6. The heat dissipation system as claimed in claim 5, wherein the slots of the holder of the air guiding member each have a V-shaped configuration.
 7. The heat dissipation system as claimed in claim 6, wherein two adjacent ones of the four slots of the holder each have an angle not larger than 90 degrees, the other two adjacent ones of the four slots each having an angle larger than 90 degrees, when one of the clasps of the body is blocked in one of the two adjacent ones of the four slots having an angle not larger than 90 degrees, the wing of the air guiding member being positioned to be parallel to the cooling air passage, when the one of the clasps is blocked in the other one of the two adjacent ones of the four slots having an angle not larger than 90 degrees, the wing being positioned to be perpendicular to the cooling air passage.
 8. The heat dissipation system as claimed in claim 1, wherein non-fins are located at a side of the base to define a blank region for forming the cooling air passage.
 9. The heat dissipation system as claimed in claim 1, wherein a width of the cooling air passage is larger than that of the heat exchange passage.
 10. A heat dissipation system for dissipating heat generated by two electronic members in a computer system comprising: an airflow path in the computer system; a first heat dissipation device located in the airflow path and near an intake of the airflow path, the first heat dissipation device comprising a first heat exchange passage and a first cooling air passage being parallel to the first heat exchange passage; and a second heat dissipation device located in the airflow path and away from the intake of the airflow path, the second heat dissipation device comprising a second heat exchange passage and a second cooling air passage, the second heat exchange passage and the second cooling air passage being parallel to the first heat exchange passage of the first heat dissipation device; wherein the first cooling air passage of the first heat dissipation device is open, and the second cooling air passage of the second heat dissipation device is close.
 11. The heat dissipation system as claimed in claim 10, wherein the first heat dissipation device is the same as the second heat dissipation device.
 12. The heat dissipation system as claimed in claim 11, wherein the first cooling air passage of the first heat dissipation device faces the second heat exchange passage of the second heat dissipation device.
 13. The heat dissipation system as claimed in claim 11, wherein the first and second heat dissipation devices each comprise a base and a plurality of parallel spaced fins extending upwardly from the base, the fins of the first heat dissipation device defining the first heat exchange passage therebetween, the fins of the second dissipation device defining the second heat exchange passage therebetween, non-fins being located at a side of the base, the non-fins located at a side of the base of the first heat dissipation device forming the first cooling air passage, the non-fins located at a side of the base of the second dissipation device forming the second cooling air passage.
 14. The heat dissipation system as claimed in claim 13, wherein the first and second heat dissipation devices each further comprise an air guiding member, the air guiding member comprising a holder secured on the base, a body pivotally engaging a top of the holder, and a wing extending from an outer surface thereof.
 15. The heat dissipation system as claimed in claim 14, wherein the wing of the first heat dissipation device is located near the intake of the airflow path and is parallel to the first cooling air passage of the first heat dissipation device, the wing of the second heat dissipation device being perpendicular to the second cooling air passage of the second heat dissipation device. 